The disclosure relates generally to wireless distributed communications systems (WDCSs), including but not limited to distributed antenna systems (DASs), remote radio head (RRH) systems, and small radio cell systems, and more particularly to automatic configuration of cell assignment of non-Inter-Cell Interference Coordination (ICIC)-engaged remote units in a WDCS to non-ICIC-engaged WDCS cells to avoid or reduce dividing radio resources (e.g., radio resource matrix (RRM) resources) to remote units.
Wireless customers are increasingly demanding wireless communications services, such as cellular communications services and Wireless Fidelity (WiFi) services. Thus, small cells, and more recently WiFi services, are being deployed indoors. At the same time, some wireless customers use their wireless communications devices in areas that are poorly serviced by conventional cellular networks, such as inside certain buildings or areas where there is little cellular coverage. One response to the intersection of these two concerns has been the use of WDCSs. Examples of WDCSs include DASs, RRH systems, and small radio cell systems (e.g., femotcells systems). WDCSs include remote units configured to receive and transmit downlink communications signals to client devices within the antenna range of the respective remote units. WDCSs can be particularly useful when deployed inside buildings or other indoor environments where the wireless communication devices may not otherwise be able to effectively receive radio frequency (RF) signals from a source.
In this regard, FIG. 1 illustrates an indoor wireless distributed communications system (WDCS) 100 that is configured to distribute communications services to remote coverage areas 102(I)(1)-102(M)N), where ‘N’ is the number of remote coverage areas. The indoor WDCS 100 can be configured to support a variety of communications services that can include cellular communications services, wireless communications services, such as RF identification (RFID) tracking, WiFi, local area network (LAN), wireless LAN (WLAN), and wireless solutions (Bluetooth. WiFi Global Positioning System (GPS) signal-based, and others) for location-based services, and combinations thereof, as examples. For example, the indoor WDCS 100 may be a DAS or an RRH system. The remote coverage areas 102(1)(1)-102(M)N) are created by and centered on remote units (RUs) 104(1)(1)-104(M)(N) connected to an indoor cell 106. The remote units 104(1)(1)-104(M)N) are shown arranged in rows ‘1-M,’ each with columns ‘1-N’ for convenience, and are located in a building 108 or in an area of the building 108. The indoor cell 106 may be communicatively coupled to an outdoor cell 110, such as for example, a base transceiver station (BTS) or a baseband unit (BBU). The outdoor cell 110 is part of an outdoor communications system 111. The indoor cell 106 receives downlink communications signals 112D from either the outdoor cell 110 or other network to be communicated to the remote units 104(1)(1)-104(M)(N). As examples, the indoor cell 106 may be an RRH cell or a central unit as part of a DAS. The downlink communications signals 112D are communicated by the indoor cell 106 over a communications link 114 to the remote units 104(1)(1)-104(M)(N). The remote units 104(1)(1)-104(M)(N) are configured to receive the downlink communications signals 112D from the indoor cell 106 over the communications link 114. The remote units 104(1)(1)-104(M)(N) may include an RF transmitter/receiver (not shown) and a respective antenna operably connected to the RF transmitter/receiver to wirelessly distribute the communications services to indoor user equipment (UE) 116 within their respective remote coverage areas 102(1)(1)-102(M)(N). The remote units 104(1)(1)-104(M)N) are also configured to receive uplink communications signals 112U from the UE 116 in their respective remote coverage areas 102(1)(1)-102(M)(N) to be communicated to the indoor cell 106. The outdoor cell 110 is also configured to exchange downlink and uplink communications signals 118D, 118U to outdoor UE 120.
With continuing reference to FIG. 1, both the indoor cell 106 and the outdoor cell 110 use the same channel frequency. If no coordination exists between the outdoor cell 110 and the indoor cell 106, downlink communications signals 118D transmitted by the outdoor cell 110 to the outdoor UE 120 might be received as interference by the indoor UE 116. This can occur for indoor UE 116 that is located close to the side of the building 108 and thereby exposed to the outdoor cell 110. In addition, downlink communications signals 112D communicated from the indoor cell 106 through the remote units 104(1)(1)-104(M)(N) to the indoor UE 116 might be received as interference by the outdoor UE 120 if located close enough to the building 108 within a remote coverage area 102(1)(1)-102(M)(N). This is called “inter-cell interference.” Similar interference issues also exist for uplink communications signals 112U, 118U. To avoid collisions between the indoor and outdoor systems, Inter-Cell Interference Coordination (ICIC) is employed by the indoor cell 106 and the outdoor cell 110. ICIC is a self-organizing network (SON) feature used by neighboring cells for coordinating the usage of their time frequency resources for minimizing the occurrences where two cells assign the same radio resources simultaneously. ICIC provides a solution to inter-cell interference by applying restrictions to a radio resource matrix (RRM) managed by a cell, such as a base transceiver station (BTS), thus improving favorable channel conditions across subsets of UE that are severely impacted by the interference, and thus attaining high spectral efficiency. When ICIC is employed, the engaged cells temporarily give up part of their available time frequency resources in a way that each of the engaged cells uses a certain portion of the available time frequency resources and let the other cell use the other portion. In this manner, a collision between time frequency resources is avoided, but at the price of reduced time frequency resources available for each neighboring cell.
In this regard, with reference back to FIG. 1, employing ICIC in the indoor and outdoor cells 106, 110 causes radio resources in an RRM 122 (e.g., a radio frame) used by the outdoor cell 110 and the indoor cell 106 to be divided based on time division, frequency division, or both. In the example in FIG. 1, the indoor and outdoor cells 106, 110 divide the radio resources (e.g., radio sub-frames) between them based on time division. According to this example, the outdoor cell 110 uses radio resources 124 in the RRM 122 while the indoor cell 106 uses radio resources 126 in the RRM 122. As a result, collisions between the indoor WDCS 100 and the outdoor communications system 107 can be avoided. However, as a result, employing ICIC results in the indoor WDCS 100 only having a portion of the available radio resources of the RRM 122 available to support the indoor UE 116, although most of the area of the building 108 is not exposed to the outdoor cell 110 and thus not subject to potential interference from the outdoor cell 110.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.